Borderlands 2's budget was "way more than double", according to Randy Pitchford.
The Gearbox Software president said while the actual budget was double the original game, it's effectively around three or four times because the studio didn't have to invent a whole new game.
"Effectively [the budget is] like triple or quadruple, because in Borderlands 1 we had a lot of invention. We had to figure these things out," he said.
Comparing the inventive process to Edison inventing the lightbulb, Pitchford said it was a "very expensive" ordeal.
"He knew he could do that, in the same way we knew what's fun about the RPG is the fun of collecting loot, and levelling up and growing and making choices.
"That's not mutually exclusive with the moment-to-moment fun of a shooter, we knew that, but we hadn't figured out all the details of what that means to put those two things together.
"You fish around in the dark, you try things and they don't work, and you try other things and you learn from what you tried, and build on that."